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<div class="section" title="Multi-Agent Systems">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="spade.basic.mas"></a>Multi-Agent Systems</h2></div></div></div>
<p>A multi-agent system (MAS) is a system composed of several 
		software agents, collectively capable of reaching goals that are 
		difficult to achieve by an individual agent or monolithic system.</p>
<p>The exact nature of the agents is a matter of some controversy. 
		They are sometimes claimed to be autonomous. For example a household 
		floor cleaning robot can be autonomous in that it is dependent on a 
		human operator only to start it up. On the other hand, in practice, 
		some agents are under active human supervision, becoming interdependent 
		systems.</p>
<p>MAS systems are also referred to as "self-organized systems" as they tend 
		to find the best solution for their problems "without intervention". There is 
		high similarity here to physical phenomena, such as energy minimizing, where 
		physical objects tend to reach the lowest energy possible, within the physical 
		constrained world.</p>
<p>The main feature which is achieved when developing MAS systems
		is flexibility, since a MAS system can be added to, modified and reconstructed, 
		without the need for detailed rewriting of the application. These systems also 
		tend to be rapidly self-recovering and failure proof, usually due to the heavy 
		redundancy of components and the self managed features, referred to, above.</p>
<div class="section" title="Kickin'it FIPA style">
<div class="titlepage"><div><div><h3 class="title">
<a name="spade.basic.mas.fipa"></a>Kickin'it FIPA style</h3></div></div></div>
<p>In order to prevent the proliferation of incompatible agent systems and to promote
			the agent-based technology and the interoperability of its standards with other technologies,
			the Foundation for Intelligent Physical Agents (FIPA) was formed. It is an IEEE Computer 
			Society standards organization.</p>
<p>The FIPA has produced a set of documents (called "FIPA Specifications") that together
			conform the modern standard (or HOW-TO) in terms of agent technology. It starts with the definition
			of the agent platform, the "home" of the agents. It is the environment where the agents are placed
			and where their activities are performed. The software foundation for a MAS-based solution and
			the <span class="emphasis"><em>network server</em></span> they connect to.</p>
<p>The FIPA defines a model for an agent platform and a communication language for the agents.
			All the platforms that want to be FIPA-compliant should follow this model and understand the
			language, and SPADE is no exception. The compliance requires basically four features:</p>
<div class="itemizedlist"><ul class="itemizedlist" type="disc">
<li class="listitem"><p>An Agent Communication Channel (ACC). A mechanism which allows the agents (and the platform itself)
				to communicate with one another.</p></li>
<li class="listitem"><p>An Agent Management System (AMS). A way for the agents to be registered in the platform and to
				be reachable for contact (kind of a <span class="emphasis"><em>White Pages</em></span> service).</p></li>
<li class="listitem"><p>A Directory Facilitator (DF), which is a kind of public service in which agents publish the
				services they offer, something akin of a <span class="emphasis"><em>Yellow Pages</em></span> service.</p></li>
<li class="listitem"><p>Support for the FIPA Agent Communication Language (ACL), which is a common language for all
				agents to communicate with. Essentially, it is presented in a couple of flavors: one based on a
				Lisp-like syntax environment (using an obscene amount of parenthesis), and a clear, pure, practical and
				beautiful syntax based on XML.</p></li>
</ul></div>
<p>SPADE implements all these features (and a few others) and thus is a FIPA-compliant platform.</p>
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